package de.fuberlin.inf.alp3.ue06;

import java.security.InvalidParameterException;

abstract class BinaryOp implements Expression {
    final Expression left, right;
    BinaryOp (Expression left, Expression right) {
        if (left == null || right == null)
            throw new InvalidParameterException();
        this.left = left;
        this.right = right;
    }
     @Override
    public abstract Expression eval();
}